Abrading



Dec. 16, 1952 L. A. MARTIN EIAL ABRADING 3 Sheets-Sheet 1 Filed May 1,. 1948 5. w M 7? z WW U w4 %4 we 3% 73 Dec. 16, 1952 L. A. MARTIN EI'AL 2,621,449

ABRADING Filed May 1, 1948 3 Sheets-Sheet 2 Dec. 16, 1952 MARTlN HAL 2,621,449

ABRADING Filed May 1, 1948 3 Sheets-Sheet I5 Z" a 22 f] Patented Dec. 16, 1952 UNITED Pie- 'T E-NT @oFFIcE 2,621,449 ABRADING i liawrence A. Mai tin: and Theodore J'. Mill'er, St. Paul, and Lluellynn A. I Wright, fRobbinsdaIe,

Minn.,- assignors=to Minnesota Mining .8; -Manuf a;cturing;(lompany, St. Paul, Minn, a corporal tionr-of Delaware I kpiilica tioif May l, 1948, 5riaI No2 -24g486 ecaims. (01451-23) This invention relates 'tonma'ohin'es fors shape -"edge' grinding-ofsheets of glass are described ,grinding, e.':g., for-grinding '-curve'd= surfaces,

particularly the edges of relatively 'thin objects such as sheets of meta1,z:glass,":plasticy wood,

stone and other materials.

Heretoforesuch operations "have beemaccomlished by abrasive belt abrading or grinding machines, applying the-edge ofilthe workjpiece along the lengthof the beltandusing aback-up or' contact wheel having: aiperip'hery'complementary in shape to the desi'red' contour of the ob- .ject being-abraded. Such arrangementshave certain disadvantages.

One is the failure f the belt to bend or curve intoexact conformity with the periphery of thecontactiwheel, due-t0" the stiffness of the belt and/or :the-sharpness of the contours. Another is belt wastage;- themargins of the belt are usually untouched-in such operations.

Abrasive wheel abradingor grinding machines have also been heretofore *used, the 'wheel (like the above mentioned loelt contact wheel) having a shaped periphery complementary to the :desired .contour ofthe object beingflabralded. -A"disadwheels that will produce grind abrade and/or polish surfaces of a-given contour on hard ;materials accurately and within a minimumof belt or wheel waste.

Briefly, the invention provides for bringing the work piece into contact with .arotating -abrasive implement (ea g.,-arotating abrasivebelt contact wheel or arotating:agbrasive'wheel) and at the same time moving the implementwith its axis of rotation alwaysparallel with itselfina direction perpendicular to its axis in- 'a'path-cemplementaryto the desired contour.

The invention r-may 'be employed to "give a square or angular shaped-.-edge:a curved shape, or to polish. abrade or otherwise furthenfinish an edgethat'isalreadywurved. --It may 'also be employed to-form Or finish a-square or -straight edge.

As illustrative embodiments, an abrasive "belt machineand :anabrasive wheelrmachine for-the below and illustrated-inthe accompanying drawingsinwhich: K

Figure 1- i's'a side elevation of' an abrasivecbelt machine "WI-1111758,. portion "of the frame brok'en aWay; 7

- Figure -2 is ai-fron't elevation; I

- Figure 3* is-a planview of the 'forward pfiiti'on;

Figure 3a is a? greatly enlarged fragmentof the sectional-view or 4 one ofthe two circular oscillator? plates that appears in Figure 3, to show the shims; v

Figure 4 is an'enlarged sideelevation-of the c r;

Figure 5 is f ax. diagram showing relative-movements of 'certain- -p art s; Y

Figure ;6 is aside-elevation of an-abrasive wh l' mach v t, v. V.

Figures, 8 and Qare'diagramsof alternative r and a t. t u N Figures 10, 11, 12,13 and- 1 show-variousedge shapes thatcanbe groundon the illustrated machinea. ,7 V. t-

Three pulleys 1 l-, l 2 and-l 3;support; an endless abrasive belt l4; (Figures -1-;to 5). The belt is driven by the driving' pulley ll in: turn -is driven or rotated by: a motor- 1 5 through-adrivnsl6. s. V

Thepu-l-iey {2, which is the contact; roll -'or wheel,-is' rotatably' mounted on a spindle-pr jour- -nal l9 that is fixed a reciprocator or osicillator. lfhe 1 oscillator comprises two vertical parallel circular plates;2fi and 20" connected by a-spacer bar or girder-2]. A stationarycradleis formed oftwo upright frames 22; and- 221 havingcircular vs l h nside c ar a ks that; are s e & k t-s d n fit w h t ener p e e of the plates so :as to support the oscillate; in-a mannerto -perrnitoscillating it: about itshorizontal axis 23. The said -axis is-indicated;by the .point 23 inFigure 4, and i s s om etimes referred to For ;ease of assembly and future adjustment for wear, both of the :plate s -20 q' havevshaped peripheriesand are, split radially into two halves Y I 26 0 -and-2;2 0-"220' along the groove .of --the,-v with a, number 0f verythin 'sheets -S-*S' of m'etal inserted between the halves to serve asshi'ms. lRemovahofia'shim permits the two' halves of a lplate'i to be fdrawnfcloser together and thus take up peripheraliwear.

-rThe contact whcel -"l:2:is" rotatably mounted on the-outer or right hand surface-of the :oscillating plate 20 with its axis parallel with the ax'i's of Joscillation. Thespindle I9 is adjustably fixed in the plate so that it may be moved toward or away from the axis 23, as desired. The periphery of the contact wheel 12 is normally p0- sitioned slightly below the axis of oscillation.

The plates 2ll20 are cut away about their centers and a sector is removed from their upper portions to permit passage through the oscillator of a work piece 24 along a guide groove that is cut in a guide bar or rack 26. The plates are thus, in effect, crescent shaped, with their outer peripheries sliding in the circular tracks in the upright cradle frames 2222'.

The oscillator assembly is oscillated about its axis 23 by an arm 21 which is fixed to the spacer 2| of the assembly and is'moved up and down by a pitman 28. The pitman is operated by a crank wheel 29 which is rotated through a worm gear assembly by a motor 31. Such an arrangement produces an advantageous variable speed oscillation. When the contact wheel I2 is at the center of its oscillation, the pitman is midway of its downward (or upward) travel (Figure 1) and is moving at its fastest rate of speed. As the pitman nears the end of its stroke, its speed gradually slackens until it reaches zero at the turning point. The result is that when contacting the center of the glass where only a little abrasion is needed, the oscillating movement of the contact wheel [2 is rapid and it passes quickly over the area; but when contacting the corners where the grinding is heavy, the movement is slow and the contact wheel thus dwells longest where it is most needed.

When the oscillator 20-20 is oscillated about its axis 23 in the cradle 22-22, the rapidly spinning contact wheel I2 is reciprocated with its axis always parallel with itself (i. e., with its axis always parallel with its immediately previous position) in a direction perpendicular to its axis, in a path complementary to the surface being formed or ground. The contact point or contact line of the wheel l2 will reciprocate or oscillate in a circular path about the axis of oscillation 23, and the lower edge of the work piece 24 will be ground to a shape complementary to the said path, i. e., the piece will be given a cylindrical edge, i. e., a convex rounded edge that is circular in cross section such as 'is shown is Figure 10 or 11 (sometimes called a pencil edge). The axis of oscillation 23 lies wholly within the guide groove 25. The bottom of the groove is below the axis so that the bottom edge of the work piece 24 will contact the abrassive belt M on the contact wheel l2 when the work piece is advanced through the machine along the path defined by the groove. The path of the object lies within a plane that is determined by the axis of oscillation and that at the same time is always parallel with the axis of the contact wheel 12.

To compensate for the movement of the abrasive belt [4 that is caused by the oscillation of the contact wheel [2, and to keep the belt taut, the idler pulley I3 is rotatably mounted on an upright arm which is pivoted at 36.

A horizontal arm 3'! extending from the arm 35 is impelled downwardly by a spring 38, whereby the upright arm 35 and with it the pulley I3 is impelled forwardly to maintain a desired tension on the abrasive belt 14. The spring yields when the pulley I3 is impelled rearwardly by the belt when the contact wheel 12 moves from its center position toward either extremity of its oscillation.

Positional adjustment of the idler pulley I3 4 may be made by moving the bed plate 40 which supports the arm 35, rearwardly or forwardly by the screw assembly 4 l Where it is desired to use an abrasive wheel as the abrading implement rather than an abrasive belt, the contact wheel 12 of the described belt machine may be replaced by an abrasive wheel H2 and a driven pulley H1, both fixed to each other and journaled on the spindle l9 (Figure 6). The illustrated abrasive belt I 4 would then be replaced by a power or driving belt H4 which would drive the pulley H1 and thereby rotate the abrasive wheel H2. The operation and construction would otherwise be as herein described in connection with the use of an abrasive belt, with the wheel H2 swinging or oscillating about the axis 23 in the same manner as the abrasive belt contact wheel 12 so as to abrade the lower edge of the work piece 24. A single machine could thus be equipped with interchangeable parts so as to employ either an abrasive belt or an abrasive wheel, as desired.

It will thus be seen that the invention involves certain prescribed movements of what may accurately be termed rotating abrasive implements.

The illustrative examples of a rotating abrasive implement that are specifically described and illustrated herein are (1) an abrasive belt sive belt) and (2) an abrasive wheel.

abrasive surfaced wheels.

Other implements that abrade by being ro-. tated about their own axes with their periph-. eries in contact with the work, are also contemplated by the invention.

The abrasive wheel I I2 may be a solid abrasive wheel or it may comprise a non-abrasive core coated on its periphery with a layer or thickness of abrasive substance. The term abrasive wheel as used herein, is intended to embrace both.

Numerous other alternatives and equivalents may be employed that embody the principles of the invention. I 7

The construction of the oscillator may vary. For example, it could comprise a single plate, such as the plate 20, and such plate (or both plates if there are two) may be of a shape or design other than that illustrated as long as it will clear the work that is being passed through the machine and oscillate the contact wheel about an axis parallel with the axis of the wheel.

The path of reciprocation or oscillation of the contact wheel l2 here shown as circular, may follow the contour of other desired shapes, e. g., of an oval, an ellipse, a compound curve, a reverse curve, etc. Also the path may be straight, if desired. The non-circular curved shapes are usually used in connection with work pieces that are relatively thick.

Apparatus suitable for producing reciprocations or oscillations of the contact wheel in paths other than circular is shown in diagram in Figure 7. The abrasive belt contact roll 12 rotates on a journal I9 which is s'lidably held in a slot 45 that is cut in a stationary bearing plate 46. The journal 19' and with it the contact wheel I2 is reciprocated in the slot by a crank 29 and pitman 28'. The slot 45, here shown as of a nondiagrams:

*-- xoircular==-- curved shape:,:: may; :be ofanwdesired shapel Its shape will -be reproduceds:on itheasurface or e'dge of the' work pieceifl -being ground. For example; if the slot is a portion' ofan ellipse, the piece-Will-be given .a cylindroid edge, i. e-., a convex rounded edge-that isellipticalin cross 1 *section. If -theslotis straight, asshown i F-ig- I ure"8,=-the-- piece. =will be=given=a straightwedge,

such as the square *edge shown in -Figure -l l.

-' I-f t-he slot has a downward-curve such as shown i Y in; Figure 9, the piecewillbe given acconeave edge-such-as shown-in Eigure 13.

When the" pathof -reciprocation --cir'cular,

- "edges of -work- -pieces"will-variouslyappear as 1 shown i-rr-Figures 1-0, H and:lkdepending onthe distance---between the--contact" wh'eel andi the axis ofoscillation 23; --=In iormingthe edgeshown in" Figure 1 lr-the-pointor-iine of abrasive contact was below-the axis -a--distancerequal to half the .1

--thickness of the work piece,- and-the resultant "edge issemi-circular in 'cross section: in Figure 11 the point of abrasive contact ,was -b'elovw: the iaxis'more than half thesaid thickness "and in Figure l2thev point"of-abrasivecontact and the axis "of" oscillation" coincided." Holding" the con- --tact wheel at" onerpoint-without-reciprocation williproduce aconcave edge 'such as-that shown in"Figure"l3.

The path of movement of thework piece-herev showna-s'being along-the axis of oscillation in a straight lineto accommodate the straight edge of theillustrated-work"piece, may be curved in respect to horizontallto accommodate a work piece having a curved'edge, such as automo-x bile window glass, and-yet still be straight in respect to vertical. It would liewithin a plane that is determined by the axisiof; oscillation. Such a path is still regarded as being along the .axis of oscillation within" the, meaning (of that;

-.duced and finished edges on sheets of glass rang.

1 ing in thickness from to;

The use of the full'w'idtlfof the abrasive belt of the abrasive wheel as taught by this invention, greatly increases the life of both. As is well known, belts have long possessed advantages over -wheels-for most glass:edgi gyoperations; since,

for;example, a single belt can -give bothzheavy stock removal and fine finish in one operation, whereas a number or series of wheels are needed to accomplish the same result. The present invention now removes an important previous objection to belts, which was their length of life. Belts used according to the present invention for the edge grinding of sheets of glass have been found to possess at least ten times the life of the same belts when used in machines and methods heretofore known. Consequently, the abrasive belt machine and method provided by this invention is far superior to any means for the edge finishing of glass heretofore known.

6 'ii":The ab1-ading; or objectsiof-all r'kindsymadeiof -a-: variety;iof materials',as :previou'slytmentiened,

is: contemplated. Such aobj'ects; include :glass :aLdoors, :automobile :iwindow glass marblet-slabs,

l-aminatedwood;plasticsheetsyetc.

-T'he examples :herein show -the -abradingvot the marrow surfaces 'ofa relatively-thin objectaasuch narrow surfaces.- commonlybeing callew' the edges. 'I he abrading of. ot-her types faces howeverp is also. contemplated. Fort-ex- -ample; the edges:of ..an :-article. such-:as as sheet of glass;--may be beveled by stipping the sheet at I -an angle an'd abrading theifcornerst 01 the e'dge,

i. e.--, where; the bro'ad isurfaces'r oi the glassand the-narrow :edge 1 surface meet.

We claim: l .v=In an-'abra'ding machine an oscillatorsasse'mblyincludingetwo parallel-1 mutilated circular plates, each plate having anotch therein extending from the-periphery-to-approximatelmthe cen- --ter thereof, the-edges of each notch extending in diverging relation' irom adjacent the central. ---portions 1 of the plates to provide clearancefor the-passage of a workpiecethrough-the assembly,

and -connectingmeansmolding 'the plates togetherin-spaced relation an-assemblysupporting means comprising a--cradle-formed*-by*=two upright frames-:having circular openings *-w1th 1 inside circular tracks ---shapedto 'm-ake a -fsliding fitwith the peripheries of the plates; and a "-wheel rotatably ,moun-ted on the *assemb1y;"-the axis of the 'wheeland the" axis of oscillationf the assembly being-paral-leheind in spaced relation to eachother.

2: The, device of'cIaim 1 in whichthe plates each have V shaped: peripheries and are split radially n v on e groove of" the V with-aplurality' of sheets inserted-between the halves; and fastening 'meansfor releasablyholding the. two halves "of' each; plate together.

' i 3'; .In' an abrading' machine; '7 an oscillator assembly including'two' parallel mutilated: circular plates, each p'late having a-notjch therein extending from they periphery to approximately the; center-- thereof, the edges of each notch extending in diverging relation fromadjacent the" central portions of the plates'to providejclearancefor 'thepassage of" a workpiece through the assembly, and connecting" means holdingjthe' plates to- "gether in spaced relation; pan assemblyisupporting means comprising aicradle"formedf-by'two uprightframes having circular openings with inside circular tracks' shaped to. make} a sliding fit with the peripheries of tl' eplates ya-spindle -fixed on .the oscillator with its axis-parallel with the axis of oscillation" of the assembly and .in-spaced relation thereto; a driving pulley;1an idler pulley;

means 'for rotatably mountingthe'driving" pulley and means for rotatably mounting theidler pulley with their axes parallel .with thespindle and with the said; pulleys: andzthe spindl e'aligned-for the support of an endlessbelt when awheelis-mqunted on the spindle, the said-idler pulleymounting lator assembly including two parallel mutilated circular plates, each plate having a notch therein extending from the periphery to approximate- 7 ly the center thereof, the edges of each notch extending in diverging relation from adjacent the central portions of the plates to provide clearance for the passage of a workpiece through the assembly, and connecting means holding the plates together in spaced relation; an assembly supporting means comprising a cradle formed of two frames having circular openings with inside circular tracks shaped to make a sliding fit with the peripheries of the plates; a spindle mounted in the oscillator assembly with its axis parallel with the axis of oscillation of the assembly and in spaced relation thereto; a pulley mounted on said spindle; a driving pulley; an idler pulley; means for supporting said driving and idler pulleys for rotation about axes parallel with said spindle and in alignment with each other and with said first mentioned pulley for supporting a belt; an endless abrasive belt mounted on said pulleys; the supporting means for the idler pulley being movable to compensate for the oscillations of the spindle and being spring loaded to impart tension to the belt; means for rotating the driving pulley; means for oscillating the oscillator assembly; and guide means for conducting a workpiece along the axis of oscillation in a position to contact the abrasive belt.

5. An abrasive belt machine comprising an oscillator assembly including two parallel mutilated circular plates, each plate having a notch therein extending from the periphery to approximately the center thereof, the edges of each notch extending in diverging relation from adjacent the central portions of the plates to provide clearance for the passage of a work piece through the assembly, and connecting means holding the plates together in spaced relation; an assembly supporting means comprising a cradle formed by two upright frames having circular openings with inside circular tracks shaped to make a sliding fit with the peripheries of the plates; an abrasive belt contact wheel rotatably mounted on the oscillator with its axis parallel with the axis of oscillation of the assembly and with its periphery in spaced relation to the axis of oscillation; a driving pulley; an idler pulley; means for rotatably mounting the driving pulley and means for rotatably mounting the idler pulley with their axes parallel with the axis of the contact wheel and with the said pulleys and the said wheel aligned for the support of an endless abrasive belt, the said idler pulley mounting being movable to compensate for the oscillations of the contact wheel and spring loaded to impart tension to the belt; means for rotating the driving pulley; means for oscillating the oscillator assembly; and guide means for conducting a work piece along the axis of oscillation in contact with an abrasive belt carried by the contact wheel.

6. An abrasive wheel machine comprising an oscillator assembly including two parallel mutilated circular plates, each plate having a notch therein extending from the periphery to approximately the center thereof, the edges of each notch extending in diverging relation from adjacent the central portions of the plates to provide clearance for the passage of a work piece through the assembly, and connecting means holding the plates together in spaced relation; an assembly supporting means comprising a cradle formed by two upright frames having circular openings with inside circular tracks shaped to make a sliding fit with the peripheries of the plates; an abrasive wheel rotatably mounted on the oscillator with its axis parallel with the axis of oscillation of the assembly and with its periphery in spaced relation to the axis of oscillation; a driven pulley concentrically fixed to the abrasive wheel; a driving pulley; an idler pulley; means for rotatably mounting the driving pulley and means for rotatably mounting the idler pulley with their axes parallel with the axis of the driven pulley, and with the said pulleys aligned for the support of a power belt, the said idler pulley mounting being movable to compensate for the oscillations of the abrasive wheel and the driven pulley and being spring loaded to impart tension to the power belt; means for rotating the driving pulley; means for oscillating the oscillator assembly;

and guide means for conducting a work piece along the axis of oscillation in contact with the abrasive wheel.

LAWRENCE A. MARTIN. THEODORE J. MILLER. LLUELLYNN A. WRIGHT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 685,328 Gale Oct. 29, 1901 760,765 Stutz May 24, 1904 890,463 Sonles June 9, 1908 938,387 Keller Oct. 26, 1909 1,325,789 Johnson Dec. 23, 1919 1,415,785 Brown May 9, 1922 1,475,742 Brown Nov. 27, 1923 1,689,829 Heintz Oct. 30, 1928 1,689,928 Olsson Oct. 30, 1928 1,956,068 Herzog Apr. 24, 1934 2,009,452 Moomaw July 30, 1935 2,192,240 Richardson Mar. 5, 1940 2,231,762 Johanson Feb. 11, 1941 2,257,619 Prill Sept. 30, 1941 2,290,051 Hinkley et a1. July 14, 1942 2,312,270 Simmons Feb. 23, 1943 2,334,960 Roth et al Nov. 23, 19 13 2,367,842 Weaver Jan. 23, 1945 FOREIGN PATENTS Number Country Date 137,689 Great Britain Jan. 22, 1920 618,306 Germany Sept. 5, 1935 

